A method for separating heavy rare earth ions

Abstract

The present application belongs to the field of rare earth separation, and particularly discloses a method for separating heavy rare earth ions. In the method, a vinyl complexing agent including at least one of vinyl phosphonic acid, vinyl sulfonic acid, vinyl acetic acid or 4-vinyl benzyl chloride is used to selectively complex heavy rare earth ions in an aqueous phase, so as to obviously increase the distribution coefficient between different heavy rare earth ions. Then, the aqueous phase containing the complex of heavy rare earth ions is subjected to extraction separation of different heavy rare earth ions with an organic phase containing an extractant, so as to achieve the purpose of improving the separation efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of rare earth separation, and particularly relates to a method for separating heavy rare earth ions. BACKGROUND

[0002] Heavy rare earth elements (such as thulium Tm, ytterbium Yb, lutetium Lu, etc.) have irreplaceable application value in high-end technical fields such as permanent magnet materials, laser crystals, nuclear medicine, etc. due to their unique 4f electron layer structure and similar chemical properties. However, the differences between the ion radii of these heavy rare earths are small, and the differences between the ion radii of two heavy rare earths with adjacent atomic numbers are extremely small, for example, the ion radius difference between Lu 3+ and Yb 3+ is only 0.8 pm, and the hydration energy and coordination chemical behavior between the two are highly convergent, resulting in low separation efficiency and long stage number for traditional solvent extraction methods. Therefore, a suitable method is needed to amplify the differences between different heavy rare earths to achieve a better separation effect.

[0003] Complexation extraction is a high-efficiency separation technology based on selective complexation reaction, and is widely used in the extraction and purification of target components such as metal ions, organic acids, and biologically active substances. Its core principle is to introduce a specific complexing agent in the extraction system to form a stable complex with the substance to be separated, thereby realizing selective transfer from the aqueous phase to the organic phase. Through the selective coordination mechanism of the specific complexing agent to the rare earth ions, an ideal solution is provided to amplify the structural performance differences between heavy rare earths.

[0004] At present, a variety of aqueous phase complexing agents for adjacent rare earth separation have been developed, including citric acid, lactic acid, EDTA, DTPA, etc. These complexing agents coordinate with the rare earth ions in the aqueous phase to be separated before extraction, thereby affecting the kinetics and thermodynamics of the original extraction reaction, and to some extent, improving the separation factor of different rare earths. However, these complexing agents can only optimize the extraction separation effect between light rare earths, and have low separation efficiency between heavy rare earths, so these conventional complexing agents are not suitable for the separation between heavy rare earth ions, especially the complexation extraction system and efficient separation method for adjacent heavy rare earths are still scarce.

[0005] In summary, it is of great significance to continue to develop an efficient aqueous phase complexation assisted heavy rare earth extraction separation method. SUMMARY

[0006] In view of the low separation efficiency of the conventional complexing agent in the prior art related to the water-phase complexing-assisted heavy rare earth extraction separation method, the present application provides a heavy rare earth ion separation method, which selectively complexes heavy rare earth ions in water phase by using a specific vinyl complexing agent, so as to significantly improve the distribution coefficient between different heavy rare earth ions, and then extracts and separates different heavy rare earth ions by using the water phase containing the heavy rare earth ion complex and the organic phase containing the extractant, so as to achieve the purpose of improving the separation efficiency.

[0007] To achieve the above-mentioned purpose, the present application specifically comprises the following technical solutions:

[0008] The present application provides a heavy rare earth ion separation method, which comprises the following steps:

[0009] S1, mixing the water solution containing heavy rare earth ions with a complexing agent and performing a complexing reaction to obtain a water phase before extraction; the complexing agent comprises at least one of vinyl phosphonic acid (VPA), vinyl sulfonic acid (VSA), vinyl acetic acid (VLA) or 4-vinyl benzyl chloride (VBC);

[0010] S2, mixing the extractant with an organic solvent to obtain an organic phase before extraction;

[0011] S3, sequentially mixing, extracting and separating the water phase before extraction and the organic phase before extraction to obtain a water phase after extraction and an organic phase after extraction;

[0012] S4, recovering heavy rare earth elements from the water phase after extraction and / or the organic phase after extraction.

[0013] In the separation method of the present application, at least one of vinyl phosphonic acid (VPA), vinyl sulfonic acid (VSA), vinyl acetic acid (VLA) or 4-vinyl benzyl chloride (VBC) is used as a complexing agent, in which the vinyl group and / or the phosphonic group or the sulfonic group or the acetic group or the benzyl group serves as a complexing functional group, and the heavy rare earth ions are complexed in an aqueous solution system, so that the heavy rare earth ions with similar properties are selectively coordinated with the complexing agent to form a complex, the heavy rare earth ions exist in the form of the complex, the structural performance difference between the heavy rare earth ions is amplified, and then the aqueous phase containing the heavy rare earth ion complex is subjected to an extraction reaction with an organic phase containing an extractant. In the extraction process, different heavy rare earth ions are selectively extracted from the aqueous phase into the organic phase, so that the concentrations of different heavy rare earth ions in the aqueous phase and the organic phase change, thereby enriching certain heavy rare earth ions in a certain phase, so that the concentration of the heavy rare earth ions is higher than that in the phase before extraction, thereby realizing the separation and purification of different heavy rare earth ions. In the process, the complexing agent changes the way of directly extracting rare earth from the rare earth hydrate by the extractant in the original extraction reaction, affects the thermodynamic and kinetic processes, thereby improving the separation efficiency between the heavy rare earth ions, improving the separation coefficient and separation efficiency of the heavy rare earth ions in the extraction system, and obtaining a high extraction rate of the heavy rare earth ions in the case of one-stage extraction, thereby avoiding the defects of low separation efficiency and long series in the traditional extraction method.

[0014] Preferably, in step S1, the aqueous solution containing heavy rare earth ions includes at least two heavy rare earth ions.

[0015] Further preferably, in step S1, the aqueous solution containing heavy rare earth ions includes at least two heavy rare earth ions with adjacent atomic numbers.

[0016] Preferably, in step S1, the concentration of the heavy rare earth ions in the aqueous solution containing heavy rare earth ions is greater than or equal to 0.05 g / L, and further preferably is 0.1-10 g / L.

[0017] Preferably, in step S1, the pH value of the aqueous solution containing heavy rare earth ions is less than or equal to 4, and further preferably is 0.1-1. The separation method of the present application is suitable for the separation system of heavy rare earth ions in an acidic aqueous phase system.

[0018] Preferably, in step S1, the pH value of the aqueous solution containing heavy rare earth ions is adjusted by using a hydrochloric acid solution. The present application can be applied to the separation and purification of heavy rare earth ions in a hydrochloric acid system.

[0019] In the specific embodiment, the aqueous solution containing heavy rare earth ions is prepared by dissolving a chlorinated salt of heavy rare earth in water, or directly using a heavy rare earth raw material solution.

[0020] Further preferably, the heavy rare earth chloride salt comprises at least one of HoCl3·6H2O, ErCl3·6H2O, YCl3·6H2O, TmCl3·6H2O, YbCl3·6H2O.

[0021] Preferably, in step S1, the aqueous solution containing heavy rare earth ions comprises Yb 3+ and Lu 3+ , and the mass concentration ratio of Yb 3+ and Lu 3+ is (50-105): 1.

[0022] Preferably, in step S1, the aqueous solution containing heavy rare earth ions comprises Yb 3+ and Tm 3+ , and the mass concentration ratio of Yb 3+ and Tm 3+ is (50-105): 1.

[0023] Preferably, in step S1, the aqueous solution containing heavy rare earth ions comprises Yb 3+ and Y 3+ , and the mass concentration ratio of Yb 3+ and Y 3+ is (50-105): 1.

[0024] Preferably, in step S1, the aqueous solution containing heavy rare earth ions comprises Tm 3+ and Er 3+ , and the mass concentration ratio of Tm 3+ and Er 3+ is (0.5-10): 1.

[0025] Preferably, in step S1, the aqueous solution containing heavy rare earth ions comprises Er 3+ and Ho 3+ , and the mass concentration ratio of Er 3+ and Ho 3+ is (0.5-10): 1.

[0026] The above-mentioned vinyl-containing complexing agent of the present application can form a complex with heavy rare earth ions adjacent or not adjacent in atomic number, which is significantly different and has good reversibility, and then the complex is extracted to realize high-efficiency separation, so that the separation method of the present application can efficiently separate heavy rare earth ions adjacent or not adjacent in atomic number.

[0027] Preferably, in step S1, the molar ratio of heavy rare earth ions in the aqueous solution containing heavy rare earth ions to the complexing agent is 1:(1-12).

[0028] Preferably, in step S1, the complexing reaction is performed for 60-300 s.

[0029] Preferably, in step S2, the extractant comprises at least one of 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester (P507) or di(2-ethylhexyl)phosphate (P204).

[0030] Preferably, in step S2, the organic solvent comprises at least one of n-heptane or sulfonated kerosene.

[0031] Preferably, in step S2, the volume percentage content of the extractant in the pre-extraction organic phase is 5%-20%.

[0032] Preferably, in step S3, the volume ratio of the pre-extraction aqueous phase to the pre-extraction organic phase is 1: (0.5-5).

[0033] Preferably, in step S3, the extraction is performed under oscillation or stirring, and the extraction is performed for 5-12 h.

[0034] Preferably, in step S3, the phase separation is performed by standing, and the phase separation is performed for 5-10 min.

[0035] Compared with the prior art, the present application has the following beneficial effects: in the separation method of the present application, a vinyl complexing agent comprising at least one of vinyl phosphonic acid, vinyl sulfonic acid, vinyl acetic acid or 4-vinyl benzyl chloride is used to selectively complex heavy rare earth ions in an aqueous phase, so as to significantly improve the distribution coefficient between different heavy rare earth ions, and then the aqueous phase containing the complex of heavy rare earth ions is subjected to extraction with an organic phase containing an extractant to separate different heavy rare earth ions, so as to achieve the purpose of improving the separation efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The extraction rate and separation factor of the Lu / Yb complexing extraction separation system in Example 1 and Comparative Example 1 are shown in the following graph, wherein Without in the graph represents Comparative Example 1, and With VPA represents Example 1.

[0037] Figure 2 The extraction rate and separation factor of the Yb / Tm complexing extraction separation system in Examples 2-5 and Comparative Example 2 are shown in the following graph, wherein Without in the graph represents Comparative Example 2, and With VPA, With VSA, With VLA and With VBC represent Examples 2, 3, 4 and 5, respectively.

[0038] Figure 3 The graphs show the extraction rate and separation factor of the Yb / Y complex extraction and separation system in Examples 6-9 and Comparative Example 3. In the graphs, Without represents Comparative Example 3, and With VPA, With VSA, With VLA, and With VBC represent Examples 6, 7, 8, and 9, respectively.

[0039] Figure 4 The graphs show the extraction rate and separation factor of the Tm / Er complex extraction separation system in Examples 10-13 and Comparative Example 4. In the graphs, Without represents Comparative Example 4, and With VPA, With VSA, With VLA, and With VBC represent Examples 10, 11, 12, and 13, respectively.

[0040] Figure 5 The graphs show the extraction rate and separation factor of the Er / Ho complex extraction separation system in Examples 14-16 and Comparative Example 5. In the graphs, Without represents Comparative Example 5, and With VPA, With VSA, and With VLA represent Examples 14, 15, and 16, respectively.

[0041] Figure 6 The UV-Vis spectra of Yb ions, VPPA, and Yb ion-VPA complexes in the examples are shown. Detailed Implementation

[0042] To better illustrate the purpose, technical solution, and advantages of this invention, specific embodiments will be used to further explain the invention below. Unless otherwise specified, the test methods used in the embodiments and / or comparative examples are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available.

[0043] Example 1

[0044] The Lu / Yb complex extraction and separation system for high-concentration Yb specifically includes the following steps:

[0045] (1) Dissolve LuCl3·6H2O and YbCl3·6H2O in water to make Lu 3+ and Yb 3+ The concentrations were 0.1 g / L and 10 g / L, respectively, and the pH of the solution was adjusted to 0.5 using 12 mol / L hydrochloric acid to prepare Lu.3+ and Yb 3+ mass concentration ratio of 1:100 containing heavy rare earth ions (Lu 3+ and Yb 3+ ), and the corresponding values were used to simulate the adjacent heavy rare earth raw material solution to be extracted and purified;

[0046] (2) The Yb 3+ and vinyl phosphonic acid (VPA) were allowed to stand for 1 min at a molar concentration ratio of 1:6 to fully complex with heavy rare earth ions, obtaining the pre-extraction aqueous phase, wherein the VPPA concentration was 0.3 mol / L;

[0047] (3) 50 mL of P507 and 450 mL of n-heptane were mixed and diluted to obtain a pre-extraction organic phase with a P507 concentration of 10 vol%;

[0048] (4) The pre-extraction organic phase was added to the pre-extraction aqueous phase at a volume ratio of 1:1, and oscillated for 480 min to fully contact and extract;

[0049] (5) After oscillation, the organic phase and the aqueous phase were fully separated after standing for 15 min, obtaining the post-extraction aqueous phase and the post-extraction organic phase;

[0050] (6) The heavy rare earth ions in the two phases were recovered respectively, and the recovered heavy rare earths could be used for the preparation of rare earth oxides and the like.

[0051] After extraction, the two heavy rare earth ions in the aqueous phase were selectively extracted into the organic phase, so that part of the Lu 3+ and Yb 3+ existed in the above two phases, but the concentration ratio of the two heavy rare earth ions in the two phases was different, resulting in changes in the concentrations of the two rare earth ions in the aqueous phase and the organic phase, thereby realizing purification. The concentrations of each heavy rare earth ion in the two phases were tested, and the extraction rates and separation coefficients of the two heavy rare earth ions were calculated, as shown in Table 1.

[0052] Example 2-5

[0053] A high-concentration Yb Yb / Tm complex extraction separation system, specifically including the following steps:

[0054] (1) TmCl3·6H2O and YbCl3·6H2O were dissolved in water, so that the concentrations of Tm 3+ and Yb 3+ were 0.1 g / L and 10 g / L respectively, and 12 mol / L hydrochloric acid was used to adjust the pH of the solution to 0.5, to prepare a solution containing heavy rare earth ions (Tm 3+ and Yb 3+ with a mass concentration ratio of 1:100; 3+ and Yb3+ ) solution to simulate the adjacent heavy rare earth raw material solution to be extracted and purified;

[0055] (2) According to Yb 3+ and Yb 3+ , the molar concentration ratio of the complexing agent is 1:6, and the complexing agent is added to the solution containing heavy rare earth ions (Tm 3+ ) to make it fully complexed with heavy rare earth ions after standing for 1 min to obtain the aqueous phase before extraction; wherein the corresponding complexing agents of examples 2-5 are vinyl phosphonic acid (VPA), vinyl sulfonic acid (VSA), vinyl acetic acid (VLA), and 4-vinyl benzyl chloride (VBC), and the concentration of each complexing agent is 0.3 mol / L;

[0056] (3) 50 mL of P507 and 450 mL of n-heptane are mixed and diluted to obtain an organic phase before extraction with a concentration of 10 vol% P507;

[0057] (4) After adding the organic phase before extraction to the aqueous phase before extraction according to a volume ratio of 1:1, oscillate for 480 min to make them fully contact and extract;

[0058] (5) After oscillation, stand for 15 min to make the organic phase and the aqueous phase fully separate to obtain the aqueous phase after extraction and the organic phase after extraction.

[0059] (6) The heavy rare earth ions in the two phases are recovered respectively, and the recovered heavy rare earth can be used for preparing rare earth oxides and the like.

[0060] After extraction, the two heavy rare earth ions in the aqueous phase are selectively extracted into the organic phase, so that there are some Tm 3+ and Yb 3+ in the above two phases, but the concentration ratio of the two heavy rare earth ions in the two phases is different, so that the concentration of the two rare earth ions in the aqueous phase and the organic phase changes, thereby realizing purification. The concentration of each heavy rare earth ion in the two phases is tested respectively, and the extraction rate and separation coefficient of the two heavy rare earth ions are calculated, as shown in Table 1.

[0061] Examples 6-9

[0062] The Yb / Y complex extraction separation system with high concentration of Yb includes the following steps:

[0063] (1) Dissolve YbCl3·6H2O and YCl3·6H2O in water to make the concentration of Yb 3+ and Y 3+ be 10 g / L and 0.1 g / L respectively, and use 12 mol / L hydrochloric acid to adjust the pH of the solution to 0.5 to prepare a Yb 3+ and Y 3+The solution containing heavy rare earth ions (Yb 3+ and Y 3+ ) has a mass concentration ratio of 100:1, so as to simulate the heavy rare earth raw material solution to be extracted and purified.

[0064] (2) The complexing agent is added to the solution containing heavy rare earth ions (Yb 3+ and Y 3+ and Y 3+ ) at a molar concentration ratio of 1:6, and is allowed to stand for 1 min to fully complex with the heavy rare earth ions, to obtain the aqueous phase before extraction; wherein the corresponding complexing agents in Examples 6-9 are vinyl phosphonic acid (VPA), vinyl sulfonic acid (VSA), vinyl acetic acid (VLA), and 4-vinyl benzyl chloride (VBC), and the concentration of each complexing agent is 0.3 mol / L.

[0065] (3) 50 mL of P507 and 450 mL of n-heptane are mixed and diluted to obtain an organic phase before extraction with a concentration of 10 vol% P507;

[0066] (4) The organic phase before extraction is added to the aqueous phase before extraction at a volume ratio of 1:1, and is shaken for 6 h to allow full contact for extraction;

[0067] (5) After shaking, the organic phase and the aqueous phase are fully separated after standing for 10 min, to obtain the aqueous phase after extraction and the organic phase after extraction.

[0068] (6) The heavy rare earth ions in the two phases are recovered respectively, and the recovered heavy rare earth can be used for preparing rare earth oxides and the like.

[0069] After extraction, the two heavy rare earth ions in the aqueous phase are selectively extracted into the organic phase, so that part of Yb 3+ and Y 3+ exists in the above two phases, but the concentration ratio of the two heavy rare earth ions in the two phases is different, so that the concentration of the two rare earth ions in the aqueous phase and the organic phase changes, thereby realizing purification. The concentration of each heavy rare earth ion in the two phases is tested respectively, and the extraction rate and the separation coefficient of the two heavy rare earth ions are calculated, as shown in Table 1.

[0070] Examples 10-13

[0071] A Tm / Er complexing extraction separation system under the same concentration of Tm and Er, specifically comprising the following steps:

[0072] (1) TmCl3·6H2O and ErCl3·6H2O are dissolved in water to make the concentration of Er 3+ and Tm 3+The concentrations were 10 g / L and 10 g / L, respectively, and the pH of the solution was adjusted to 0.5 using 12 mol / L hydrochloric acid to prepare Er 3+ and Tm 3+ Heavy rare earth ion (Er) with a mass concentration ratio of 1:1 3+ and Tm 3+ A solution of ) was used to simulate the adjacent heavy rare earth raw material solution to be extracted and purified;

[0073] (2) According to Tm 3+ The molar concentration ratio of the complexing agent to the complexing agent is 1:6, to the heavy rare earth ion-containing (Er) 3+ and Tm 3+ Add a complexing agent to the solution of ), let it stand for 1 min to allow it to fully complex with the heavy rare earth ions, and obtain the aqueous phase before extraction; wherein, the complexing agents corresponding to Examples 10-13 are vinylphosphonic acid (VPA), vinylsulfonic acid (VSA), vinylacetic acid (VLA), and 4-vinylbenzyl chloride (VBC), and the concentration of each complexing agent is 0.3 mol / L.

[0074] (3) Mix and dilute 50 mL of P507 with 450 mL of n-heptane to obtain an organic phase before extraction with a concentration of 10 vol% P507;

[0075] (4) Add the organic phase before extraction to the aqueous phase before extraction at a volume ratio of 1:1 and shake for 6 hours to ensure full contact for extraction;

[0076] (5) After shaking, let stand for 10 minutes to allow the organic phase and aqueous phase to fully separate into layers, and obtain the extracted aqueous phase and the extracted organic phase.

[0077] (6) The heavy rare earth ions in the two phases are recovered separately. The recovered heavy rare earths can be used to prepare rare earth oxides, etc.

[0078] After extraction, the two heavy rare earth ions in the aqueous phase were selectively extracted into the organic phase, resulting in the presence of some Er in both phases. 3+ and Tm 3+ However, the different concentration ratios of the two heavy rare earth ions in the two phases cause variations in the concentrations of the two rare earth ions in the aqueous and organic phases, thereby achieving purification. The concentrations of each heavy rare earth ion in the two phases were measured separately, and the extraction rates and separation coefficients of the two heavy rare earth ions were calculated, as shown in Table 1.

[0079] Examples 14-16

[0080] The Er / Ho complex extraction separation system at the same concentrations of Er and Ho specifically includes the following steps:

[0081] (1) Dissolve HoCl3·6H2O and ErCl3·6H2O in water, so that ErCl3·6H2O 3+ and Ho 3+ The concentrations were 10 g / L and 10 g / L, respectively, and the pH of the solution was adjusted to 0.5 using 12 mol / L hydrochloric acid to prepare Er 3+ and Ho 3+ Heavy rare earth ion (Er) with a mass concentration ratio of 1:1 3+ and Ho 3+ A solution of ) was used to simulate the adjacent heavy rare earth raw material solution to be extracted and purified;

[0082] (2) According to Er 3+ The molar concentration ratio of the complexing agent to the complexing agent is 1:6, to the heavy rare earth ion-containing (Er) 3+ and Ho 3+ Add a complexing agent to the solution of ), let it stand for 1 min to allow it to fully complex with the heavy rare earth ions, and obtain the aqueous phase before extraction; wherein, the complexing agents corresponding to Examples 14-16 are vinylphosphonic acid (VPA), vinyl sulfonic acid (VSA), and vinyl acetic acid (VLA), and the concentration of each complexing agent is 0.3 mol / L.

[0083] (3) Mix and dilute 50 mL of P507 with 450 mL of n-heptane to obtain an organic phase before extraction with a concentration of 10 vol% P507;

[0084] (4) Add the organic phase before extraction to the aqueous phase before extraction at a volume ratio of 1:1 and shake for 6 hours to ensure full contact for extraction;

[0085] (5) After shaking, let stand for 10 minutes to allow the organic phase and aqueous phase to fully separate into layers, and obtain the extracted aqueous phase and the extracted organic phase.

[0086] (6) The heavy rare earth ions in the two phases are recovered separately. The recovered heavy rare earths can be used to prepare rare earth oxides, etc.

[0087] After extraction, the two heavy rare earth ions in the aqueous phase were selectively extracted into the organic phase, resulting in the presence of some Er in both phases. 3+ and Ho 3+ However, the different concentration ratios of the two heavy rare earth ions in the two phases cause variations in the concentrations of the two rare earth ions in the aqueous and organic phases, thereby achieving purification. The concentrations of each heavy rare earth ion in the two phases were measured separately, and the extraction rates and separation coefficients of the two heavy rare earth ions were calculated, as shown in Table 1.

[0088] Example 17

[0089] Compared with Example 2, the difference is that in step (3), the organic phase of the extractant P507 in this example is replaced with P204 in equal volume, and the rest is the same.

[0090] Comparative Example 1

[0091] Compared with Example 1, the difference is that this comparative example lacks step (2), and the rest is the same.

[0092] Comparative Example 2

[0093] Compared with Example 2, the difference is that this comparative example lacks step (2), and the rest is the same.

[0094] Comparative Example 3

[0095] Compared with Example 6, the difference is that this comparative example lacks step (2), and the rest is the same.

[0096] Comparative Example 4

[0097] Compared with Example 10, the difference is that this comparative example lacks step (2), and the rest is the same.

[0098] Comparative Example 5

[0099] Compared with Example 14, the difference is that this comparative example lacks step (2), and the rest is the same.

[0100] Comparative Example 6

[0101] Compared with Example 2, the difference is that the complexing agent in step (2) of this comparative example is replaced with ethylenediaminetetraacetic acid (EDTA) in equal amount, and the rest is the same.

[0102] Comparative Example 7

[0103] Compared with Example 2, the difference is that the complexing agent in step (2) of this comparative example is replaced with citric acid (CA) in equal amount, and the rest is the same.

[0104] In M represents a heavy rare earth element, M1, M2 represent a first heavy rare earth element and a second heavy rare earth element respectively, and other heavy rare earth elements are represented in the same way. In this paper, the extraction rate (%) = c1 / c0 x 100, c0 is the concentration of M ion in the aqueous phase before extraction, and c1 is the concentration of M ion in the organic phase after extraction. Different heavy rare earth elements are calculated independently. The higher the extraction rate, the higher the purity of a certain heavy rare earth ion in the aqueous phase after extraction. The separation coefficient β is used to measure the separation and purification of two (represented by M1 and M2) heavy rare earth elements, where β M1 / M2 = (C M1O / C M1W ) / (C M2O / C M2W ), where C M1O , CM1W C represents the concentration of M1 ions in the organic phase and the aqueous phase after extraction, respectively. M2O C M2W β represents the concentration of M2 ions in the organic phase and the aqueous phase after extraction, respectively. M1 / M2 The higher the value, the higher the separation efficiency of the two heavy rare earth elements, M1 and M2.

[0105] Table 1

[0106]

[0107] Detection of the complex: YbCl3·6H2O was dissolved in water to a concentration of 0.05 mol / L, and the pH was adjusted to 0.5 with hydrochloric acid to obtain a Yb solution. A small amount of the above Yb solution was added to an excess of vinylphosphonic acid (5 mol / L) aqueous solution. The UV-Vis spectrophotometers of the vinylphosphonic acid aqueous solution, the Yb solution, and the mixture of the two were then tested. The test results are as follows: Figure 6 As shown. By Figure 6 It can be seen that the Yb solution does not have an absorption peak in the ultraviolet wavelength range; the vinylphosphonic acid aqueous solution has a spectral peak at about 237 nm; the solution after mixing the two retains the original vinylphosphonic acid solution's ultraviolet absorption peak at 237 nm, and a new characteristic peak is formed at 295 nm; it can be seen that the new characteristic peak at 295 nm verifies the formation of the Yb complex.

[0108] From Example 1 and Comparative Example 1 Figure 1 It can be seen that in the presence of Lu 3+ and Yb 3+ After adding the complexing agent vinylphosphonic acid (VPPA) to the solution for complexation, this solution is used as the aqueous phase for extraction and phase separation with an organic phase containing an extractant. Compared to the system without the complexing agent in the aqueous phase, the Lu / Yb separation coefficient β of the system of this invention is higher. Lu / Yb The value increased by approximately 30%.

[0109] From Examples 2-5 and Comparative Example 2 Figure 2 It can be seen that in the presence of Yb 3+ and Tm 3+ The solution was complexed with complexing agents vinylphosphonic acid (VPA), vinylsulfonic acid (VSA), vinylacetic acid (VLA), and 4-vinylbenzyl chloride (VBC), respectively, and then used as the aqueous phase for extraction and phase separation with an organic phase containing an extractant. Compared to the system without complexing agents in the aqueous phase, the system of this invention exhibits a higher Yb / Tm separation coefficient β. Yb / Tm The value increases by approximately 25% to 50%.

[0110] From Examples 6-9 and Comparative Example 3Figure 3 It can be seen that in the presence of Yb 3+ and Y 3+ The solution was complexed with complexing agents vinylphosphonic acid (VPA), vinylsulfonic acid (VSA), vinylacetic acid (VLA), and 4-vinylbenzyl chloride (VBC), respectively, and then used as the aqueous phase for extraction and phase separation with an organic phase containing an extractant. Compared to the system without complexing agents in the aqueous phase, the Yb / Y separation coefficient β of the system of this invention is higher. Yb / Y The value increases by approximately 60% to 70%.

[0111] Examples 10-13 and Comparative Example 4 Figure 4 It can be seen that in the presence of Tm 3+ and Er 3+ The solution was complexed with complexing agents vinylphosphonic acid (VPA), vinylsulfonic acid (VSA), vinylacetic acid (VLA), and 4-vinylbenzyl chloride (VBC), respectively, and then used as the aqueous phase for extraction and phase separation with an organic phase containing an extractant. Compared to the system without complexing agents in the aqueous phase, the Tm / Er separation coefficient β of the system of this invention is higher. Tm / Er The value increases by approximately 15% to 25%.

[0112] From Examples 14-16 and Comparative Example 5 Figure 5 It can be seen that in the presence of Er 3+ and Ho 3+ The solution was complexed with complexing agents vinylphosphonic acid (VPA), vinylsulfonic acid (VSA), and vinylacetic acid (VLA), respectively, and then used as the aqueous phase for extraction and phase separation with an organic phase containing an extractant. Compared to the system without complexing agents in the aqueous phase, the system of this invention has a higher Er / Ho separation coefficient β. Er / Ho The value increases by approximately 10% to 40%.

[0113] As shown in Examples 2 and Comparative Examples 6-7, replacing the complexing agent with other complexing agents besides vinylphosphonic acid (VPA), vinylsulfonic acid (VSA), vinylacetic acid (VLA), or 4-vinylbenzyl chloride (VBC) significantly reduced the separation coefficients of the two heavy rare earth ions. Therefore, the complexing agents of the present invention—vinylphosphonic acid (VPA), vinylsulfonic acid (VSA), vinylacetic acid (VLA), or 4-vinylbenzyl chloride (VBC)—can significantly improve the partition coefficients between heavy rare earth ions, enhance their separation efficiency, and further improve the purity of a certain heavy rare earth ion in a particular phase.

[0114] It should be noted that the above embodiments are only part of the embodiments of the present application, and the present application further includes various embodiments corresponding to the separation products obtained by changing the types and mixing ratios of the rare earth chloride salts in step (1), changing the extractant and concentration in step (3), changing the molar concentration ratio of the rare earth ions and the complexing agent in step (2), changing the volume ratio of the organic phase and the aqueous phase before extraction in step (4), and the like.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A method for separating heavy rare earth ions, characterized in that, Includes the following steps: S1. An aqueous solution containing heavy rare earth ions is mixed with a complexing agent and subjected to a complexation reaction to obtain an aqueous phase before extraction; the complexing agent includes at least one of vinylphosphonic acid, vinylsulfonic acid, vinylacetic acid, or 4-vinylbenzyl chloride; the pH value of the aqueous solution containing heavy rare earth ions is less than or equal to 4. S2. Mix the extractant with the organic solvent to obtain the organic phase before extraction; S3. The aqueous phase before extraction and the organic phase before extraction are mixed, extracted and separated in sequence to obtain the aqueous phase after extraction and the organic phase after extraction. S4. Recover heavy rare earth elements from the aqueous phase and / or the organic phase after extraction.

2. The method for separating heavy rare earth ions as described in claim 1, characterized in that, In step S1, the aqueous solution containing heavy rare earth ions includes at least two types of heavy rare earth ions.

3. The method for separating heavy rare earth ions as described in claim 2, characterized in that, Includes at least one of the following A through E: A. In step S1, the aqueous solution containing heavy rare earth ions includes Yb. 3+ and Lu 3+ The Yb 3+ and Lu 3+ The mass concentration ratio is (50-105):1; B. In step S1, the aqueous solution containing heavy rare earth ions includes Yb. 3+ and Tm 3+ The Yb 3+ and Tm 3+ The mass concentration ratio is (50-105):1; C. In step S1, the aqueous solution containing heavy rare earth ions includes Yb. 3+ and Y 3+ The Yb 3+ and Y 3+ The mass concentration ratio is (50-105):1; D. In step S1, the aqueous solution containing heavy rare earth ions includes Tm. 3+ and Er 3+ The Tm 3+ and Er 3+ The mass concentration ratio is (0.5-10):1; E. In step S1, the aqueous solution containing heavy rare earth ions includes Er. 3+ and Ho 3+ The Er 3+ and Ho 3+ The mass concentration ratio is (0.5-10):

1.

4. The method for separating heavy rare earth ions as described in claim 1, characterized in that, In step S1, the molar ratio of heavy rare earth ions in the aqueous solution containing heavy rare earth ions to the complexing agent is 1:(1-12).

5. The method for separating heavy rare earth ions as described in claim 1, characterized in that, In step S2, the extractant includes at least one of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester or di(2-ethylhexyl) phosphate.

6. The method for separating heavy rare earth ions as described in claim 1, characterized in that, In step S2, the organic solvent includes at least one of n-heptane or sulfonated kerosene.

7. The method for separating heavy rare earth ions as described in claim 1, characterized in that, In step S2, the volume percentage of the extractant in the organic phase before extraction is 5%-20%.

8. The method for separating heavy rare earth ions as described in claim 1, characterized in that, In step S3, the volume ratio of the pre-extraction aqueous phase to the pre-extraction organic phase is 1:(0.5-5).

9. The method for separating heavy rare earth ions as described in claim 1, characterized in that, In step S3, the extraction is carried out under oscillation or stirring, and the extraction time is 5-12 hours.

10. The method for separating heavy rare earth ions as described in claim 1, characterized in that, In step S3, the phase separation is carried out by a static setting method, and the phase separation time is 5-10 minutes.

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